It is a matter of course that an architectural panel must satisfy various conditions required for an architectural material, such as, strength, weathering resistance, heat insulating properties, water resistance, etc. However, the architectural panel must satisfy, in addition to these physical requirements, design requirements which appeal to the sense of sight of man. It is well known that recent technical progress has lead to the development of architectural materials which meet the previously mentioned requirements, and many different types of architectural materials are now on the market. For example, metal sheets designed for use on architectural external walls include colored iron sheets (ie., precoated galvanized sheets), PVC coated steel sheets, aluminum sheets, etc. Although oganic materials (e.g., synthetic resins) and inorganic materials (e.g., slate and plaster boards) are in use, metallic sheets are used in far greater amounts owing to ease of working, ease of mass production at relatively low cost and other reasons. However, the properties peculiar to metallic sheets, e.g., smoothness and lightweight properties and the hand and feel peculiar to metallic sheets will function adversely in the case of architectural materials depending on applications. Particularly, in consideration of design requirements appealing to the sense of sight of man, it is not infrequent that metallic sheets will be used in limited applications or they will be replaced by other materials such as wood and stone.
The recent tendency is toward adding desired organic and/or inorganic features to metallic materials. For example, the previously mentined PVC coated steel sheet is representative of this type of material and it is produced by applying an organic PVC coating to the metallic surface of a steel sheet. Another example is one produced by sprinkling and sticking inorganic sand to the surface of a colored iron sheet to provide it with a mortar-like appearance. However, to the best of the inventor's knowledge, the architectural materials known in the art are all such that their hand and feed are not changed substantially. To be more precise, even if a metallic material is changed to some extent, an observer will still feel the texture and appearance of the metallic sheet itself. While many reasons may be conceived, the most essential reason is the fact that since practically all the known architectural panels have a decorative surface layer produced by applying a coating or spreading sand uniformly on the smooth surface of the base material, those architectural panels have the disadvantages of lacking a three-dimensional effect, showing the uniform feel of products produced by machinery, lacking a pleasing appearance owing to a lack of unbalance and a tendency of the sand on the base material to fall off and after all showing only the feel of the base material itself.